Add support and tests for reverse resolving

Author: livid

Sources/ENSKit/ENSKit.swift

@@ -57,6 +57,15 @@ public struct ENSKit {
         return nil
     }
 
+    public func name(addr: String) async -> String? {
+        let reversedDomain = addr.lowercased().replacingOccurrences(of: "0x", with: "") + ".addr.reverse"
+        if let resolver = try? await resolver(name: reversedDomain),
+           let name = try? await resolver.name() {
+            return name
+        }
+        return nil
+    }
+
     public func text(name: String, key: String) async -> String? {
         if let resolver = try? await resolver(name: name),
            let text = try? await resolver.text(key: key) {

Sources/ENSKit/ENSResolver.swift

@@ -34,6 +34,13 @@ public struct ENSResolver {
         return nil
     }
 
+    public func name() async throws -> String? {
+        if let name: String = try await resolver.name(namehash: namehash) {
+            return name
+        }
+        return nil
+    }
+
     public func avatar() async throws -> Data? {
         if let avatar = try await getAvatar(),
            let url = try await getAvatarImageURL(from: avatar),

Sources/ENSKit/EthereumContract/PublicResolverContract.swift

@@ -8,6 +8,7 @@ struct PublicResolverContract: BaseContract {
     var interfaces = [
         "supportsInterface": "01ffc9a7",    // supportsInterface(bytes4)
         "addr": "3b3b57de",                 // addr(bytes32)
+        "name": "691f3431",                 // name(bytes32)
         "text": "59d1d43c",                 // text(bytes32,string)
         "contenthash": "bc1c58d1"           // contenthash(bytes32)
     ]
@@ -42,6 +43,18 @@ struct PublicResolverContract: BaseContract {
         return nil
     }
 
+    func name(namehash: Data) async throws -> String? {
+        let data = "0x" + interfaces["name"]! + ContractEncoder.bytes(namehash)
+        let result = try await ethCall(data)
+        let s = result.stringValue
+        if let (at, _) = ContractDecoder.int(s),
+           let name = ContractDecoder.string(s, at: at),
+           !name.isEmpty {
+            return name
+        }
+        return nil
+    }
+
     func addrChangedEvents(namehash: Data) async throws -> [ContractEvent] {
         let namehashTopic = "0x" + ContractEncoder.bytes(namehash)
         let result = try await ethGetLogs(topics: [

Tests/ENSKitTests/ENSKitTests.swift

@@ -45,6 +45,11 @@ final class ENSKitTests: XCTestCase {
         XCTAssertEqual(vitalikAddr, "d8dA6BF26964aF9D7eEd9e03E53415D37aA96045")
     }
 
+    func testName() async throws {
+        let vitalikName = await main.name(addr: "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045")
+        XCTAssertEqual(vitalikName, "vitalik.eth")
+    }
+
     func testText() async throws {
         let coaEmail = await main.text(name: "coa.eth", key: "email")
         XCTAssertEqual(coaEmail, "[email protected]")

Tests/ENSKitTests/EthereumContractTests/PublicResolverContractTests.swift

@@ -5,8 +5,10 @@ final class PublicResolverContractTests: XCTestCase {
     // Test against .eth public resolver with Infura Ethereum API (please do not abuse my project id)
     let client = InfuraEthereumAPI(url: URL(string: "https://mainnet.infura.io/v3/4cd2c3b40ea8423fa889fc479e05f082")!)
     let resolverAddress = try! Address("0x4976fb03c32e5b8cfe2b6ccb31c09ba78ebaba41")
+    let reverseResolverAddress: Address = try! Address("0x5fbb459c49bb06083c33109fa4f14810ec2cf358")
     let vitalik = Namehash.namehash("vitalik.eth")
     let planetable = Namehash.namehash("planetable.eth")
+    let vitalikAddressReversed = Namehash.namehash("d8da6bf26964af9d7eed9e03e53415d37aa96045.addr.reverse")
 
     func testSupportsInterface() async throws {
         let contract = PublicResolverContract(client: client, address: resolverAddress)
@@ -28,6 +30,12 @@ final class PublicResolverContractTests: XCTestCase {
         XCTAssertEqual(vitalikAddress!, try! Address("0xd8da6bf26964af9d7eed9e03e53415d37aa96045"))
     }
 
+    func testName() async throws {
+        let contract = PublicResolverContract(client: client, address: reverseResolverAddress)
+        let vitalikDomain = try await contract.name(namehash: vitalikAddressReversed)
+        XCTAssertEqual(vitalikDomain!, "vitalik.eth")
+    }
+
     func testContentHash() async throws {
         let contract = PublicResolverContract(client: client, address: resolverAddress)
         let planetableContentHash = try await contract.contenthash(namehash: planetable)